Continuous flow biodiesel processor

ABSTRACT

A continuous flow biodiesel processor utilizing high turbulence mixing of oil being processed and a flow-through separation tank with distinct zones and recirculation draw tubes is described, along with methods for using same.

RELATED APPLICATIONS

This application claims the benefit of Ames, U.S. Provisional Appl.60/740,346 filed Nov. 28, 2005, which is incorporated herein byreference in its entirety, including drawings.

FIELD OF THE INVENTION

The present invention relates to the production of lower alkyl fattyacid esters from glycerides, and in particular to the production ofbiodiesels.

BACKGROUND OF THE INVENTION

The following discussion is provided solely to assist the understandingof the reader, and does not constitute an admission that any of theinformation discussed or references cited are prior art to the presentinvention.

A number of systems for producing alkyl esters from fatty acid solutionshave been described. Most such systems are batch processing systems, inwhich the feed oil is mixed under low or medium mixing rates with abasic catalyst (e.g., NaOH or KOH) and a lower alcohol such as methanolor ethanol. The mixture is placed in reaction and separation tanks wherethe fatty acids are allowed to react. The product alky esters andglycerin are allowed to separate by gravity and the glycerin is removedfrom the tank.

A number of systems are described in patent documents. For example,Hooker, U.S. Patent Appl. Publication 2005/0027137 indicates that itdescribes an “apparatus and method for producing fatty acid alkyl estersfrom fatty acids derived from vegetable oils and animal fats” in which amixture is emulsified as a means to reach a completed reaction state ina reaction section and “transesterification occurs when the naturalboundary surfaces of the immiscible mixture are enlarged by ultrasoniccavitation in the reaction section and the transesterification isperformed at, or near, atmospheric pressure.” (Hooker, Abstract.)

Ergun, U.S. Pat. No. 6,440,057 describes a method for producing fattyacid methyl ester from at least one of vegetable and animal with analkaline solution dissolved in alcohol to form a mixture and emulsifyingthe mixture to reach a chemical balance state in a reaction section,wherein fats are transesterified into fatty acid methyl ester, whereinborder surfaces of the mixture are enlarged by dynamic turbulence in thereaction section and the transesterification is performed underpressure, and wherein the pressure is reduced duringtransesterification. The method further includes separating residuesfrom the fatty acid methyl ester in a phase separation section afterreaching a chemical balance state.

Certain systems are described that are indicated to produce biodiesel ina continuous flow manner.

Lastella, U.S. Patent Appl. Publ. 2005/0081435 states that it “achievescontinuous flow through all the reaction vessels and separation tankswithout the need for additional pumps.” Further, the system “preferablyemploys preferably closed tanks (though preferably not sealed) toprovide for methanol recovery, and may include vertical rotating feedtubes having separators and inlet and outlet openings.” (Lastella,paragraph 12.)

Connemann et al. U.S. Pat. No. 5,354,878 describes a process wherein an“oil phase of fatty triglycerides or natural oils or fats containingfree fatty acids is subjected to catalytic transesterification”, inwhich the improvement involves a multistep sequential process of a)introducing a reaction mixture into the top of a reaction column, b)transferring the column transesterification product to a second reactor,c) washing the reaction mixture with an aqueous extractant in a firstseparator, d) introducing the washed reaction mixture with additionalalcohol and catalyst into a third reactor, e) introducing the resultingmixture into a fourth reactor and maintaining the mixture under stirringfor a further transesterification forming a reaction product having adegree of transesterification of at least 99.2%, f) introducing theresulting transesterification product and hot, aqueous extractant into asecond separator, and g) drying the transesterification product.

Hanna, U.S. Patent Appl. Publ. 2003/0032826 describes atransesterification process for the production of biodiesel, where theprocess involves introducing the triglycerides and a catalyst into areaction zone and introducing an alcohol into the feed stream within thereaction zone, where the triglyceride feed stream is characterized byhaving a Reynolds number of at least about 2100.

Connemann et al., U.S. Patent Appl. Publ. 2005/0204612 describes “aprocess for the continuous production of biodiesel from a biogenicinitial feedstock mixtures containing fat or oil with a high content offree fatty acids, as well as a device for the production of biodiesel.”

SUMMARY OF THE INVENTION

In view of the great demand for oil-based fuels, and in particular formotor vehicle fuels, there is an increasing need for alternatives topetroleum products. One such alternative is biofuels, and particularlybiodiesel. Biodiesel is generally produced from oils and/or fats fromplant and/or animal origin by esterification of glycerides and/or freefatty acids under basic or acidic conditions in the presence of a loweralkyl alcohol.

The present invention concerns simple systems typically operable atatmospheric pressure (although also adaptable for higher pressures) forproducing biodiesel, especially from vegetable oils. These systemsprovide continuous flow systems, system components, and methods forprocessing glycerides (e.g., triglycerides) to produce alkyl esters,i.e., lower alkyl fatty acid ester solutions useful as biodiesel, fromvegetable and/or animal oils and fats. Certain embodiments of thepresent systems include a high turbulence processor mixer and/or afunctionally linked zonal flow-through separation tank.

Thus, in a first aspect the invention provides a continuous flowbiodiesel processor for producing a lower alkyl fatty acid esterbiodiesel from a glyceride solution that includes a high turbulenceflow-through processor mixer, a glycerol/biodiesel separator (e.g., azonal flow-through separation tank), and a biodiesel cleaner. In thisprocessor, the glycerol/biodiesel separator receives output (e.g., atleast partially reacted glyceride solution mixed with a lower alkoxidein alcohol solution (e.g., methanolic sodium methoxide) or a lowerprimary alcohol and a catalyst (e.g., a base catalyst such as NaOH orKOH)) from the processor mixer. The biodiesel cleaner receives biodieselseparated in the separator tank and removes contaminants, e.g., polarcomponents such as residual glycerol, unreacted alcohol, water, and/orother components soluble in the alcohol and/or water, from thebiodiesel.

The present components (e.g., high turbulence processor mixers and/orflow-through zonal separator tanks) can be incorporated or combined in avariety of systems and used in various methods. Thus, in a relatedaspect, the invention concerns a system for production of biodiesel,where the system includes an oil (i.e., glyceride solution) supply(e.g., an oil storage tank), a high turbulence flow-through processormixer (e.g. as described herein), a glycerol/biodiesel separator (e.g.,a flow-through zonal separation tank as described herein) that receivesreacted glyceride solution from the processor mixer, a biodieselcleaner, and a biodiesel receiver.

In another aspect, the invention concerns a scalable processor forproduction of biodiesel from glyceride solutions; the processor includesa plurality of parallel-linked high turbulence flow-through processormixers (e.g., as described herein) which can be operated or idledindependently, at least one flow-through glycerol/biodiesel separator(e.g., a flow-through zonal separator tank) functionally linked withthose processor mixers to accept a glycerol/biodiesel mixture processedthrough at least one of the processor mixers, and at least one biodieselcleaner functionally linked with the glycerol/biodiesel separator toseparate contaminants, e.g., polar components from the biodieselsolution.

In many cases, the plurality of processor mixers is 2-4, i.e., 2, 3, or4, processor mixers.

In certain embodiments, the system includes a plurality of separatortanks; the plurality of tanks includes a separate tank functionallylinked with each of a plurality of processor mixers (e.g., with eachprocessor mixer); one or more separator tanks is supplemented with oneor more centrifuges; one or more separator tanks are replaced with acentrifuge; each separator tank is replaced with a centrifuge.

Processor mixers can also advantageously be linked in a sequentialmanner with residence chambers between each. Thus, another aspectprovides a processor for production of biodiesel from a glyceridesolution that includes a sequentially linked plurality of processorunits (e.g., 2, 3, 4, 5, 6, 7, 8, 9, 10, 2-5, 6-10, 11-15 sequentialunits) where each processor unit includes a high turbulence flow-throughprocessor mixer and a residence chamber following the processor mixer.The system further includes a linked glycerol/biodiesel separatorreceiving processed glyceride solution from the processor unit (whichmay be integral or separate from the residence chamber), and a biodieselcleaner receiving biodiesel from the separator.

In certain embodiments, the glycerol separator includes a centrifuge,flow-through separation tank, and/or a cyclone; a plurality of processorunits (e.g., each processor unit) include a glycerol separator, such asa separator including or consisting of a centrifuge, a separation tank,and/or a cyclone.

In particular embodiments, the residence chamber includes, consistsessentially of, or consists of a pipe; the residence chamber includes atank; a pipe residence chamber includes internal baffles; flow in a piperesidence chamber is plug flow; the residence time in the residencechamber is 0.5-1.0, 1.0-2.0, 2.0-5.0, 5.0-10.0, 1.0-5.0, 1.0-10.0, or2.0-7.0 minutes; a processor including pipe residence chamber isoperated under pressure greater than 1 atmosphere (e.g., 1.2-2, 2-3,3-4, 4-6, 6-10, 10-20, 20-50, 50-100, 100-150, 150-200 atmospheres(atm), at least 2, 3, 4, 5, 6, 10, 20, 50, 100, 150, 200 atm).

In particular embodiments, the processor is transportable; the processorunits are installed in a volume not exceeding, 5, 10, 20, 30, 40, 50,60, or 70 m³; the processor units of a transportable processor areinstalled in a standard 20-foot or 40-foot shipping container; theprocessor components of a processor are mounted in a volume notexceeding 5, 10, 20, 30, 40, 50, 60, or 70 m³ with the exception of theglyceride solution supply and biodiesel storage, and optionally analcohol recovery system and a biodiesel cleaner.

In some processors, the processor combines scalable and sequentialfeatures. In such aspects or embodiments, the processor includes aplurality of parallel-linked processor mixers that can be operated oridled independently, and at least one of the processor mixers (e.g., 1,2, 3, 4, or all) is sequentially linked with at least one otherprocessor mixer with a residence chamber between them. In certainembodiments, the scalable feature is as described herein for scalableprocessors and/or the sequential features are as described herein forsequential processors.

In certain embodiments of the above aspects, the high turbulenceprocessor mixer has a fluid cavity with at least two proximate opposingsurfaces. Those opposing surfaces include projections, and at least oneof the opposing surfaces rotates during use such that there is arelative velocity between the surfaces. Such rotation can be created byrotation of either surface, or counter-rotation of both. In somedesigns, the first projections and second projections bypass duringrotation.

In particular embodiments, the processor mixer includes a hollow outerhousing that has an inner surface having a plurality of firstprojections, and a proximate spaced apart inner body (located within thehollow outer housing) having an outer surface that has a plurality ofsecond projections, where the outer housing and the inner body rotaterelative to each other. In certain embodiments, the inner surface of theouter housing has a first cylindrical surface, and the outer surface ofthe inner body has a second cylindrical surface; the first and secondcylindrical surfaces are separated by an annular gap; rotation is abouta common longitudinal cylindrical axis; the longitudinal axis of thesecond cylindrical surface is offset from the longitudinal axis of thefirst cylindrical surface; the second cylindrical surface is rotated andthe first cylindrical surface is fixed; the relative velocity of thefirst and second cylindrical surfaces is at least 10, 15, 20, 25, 30,10-20, 20-30 meters per second (m/s); at least some of the projections(e.g., at least 10%, a majority, or substantially all) include asubstantially flat trailing edge surface having sharp corners andoriented substantially perpendicular to the rotation direction; at leastsome of said projections have a tapering trailing surface (e.g., atleast 10%, a majority, or substantially all).

In certain embodiments, the processor mixer includes a housing and agenerally circular rotor within that housing. The rotor has a first faceand a second face, and the rotor has a first set of projections on atleast one of its first and second faces. The housing includes a secondset of projections on an inner surface proximate to the rotor face thathas the first set of projections. In certain embodiments, the first setof projections includes a set of vanes; the vanes include a set ofconcentric gaps, and the second set of projections include a matchingset of concentric rings of projections that fit within those gaps; thehousing also includes a third set of projections on the inner surfaceproximate the distal ends of the rotor vanes; the rotor vanes alsoinclude at least one groove in their distal ends and the housing furtherincludes a third set of projections on the inner surface proximate thedistal ends of the vanes and the third set of projections project intothat groove; rotation of the rotor is driven by a central shaft drivenby an external power unit; rotation of the rotor is magnetically coupledto an external power unit.

In another variant, the processor mixer includes one or more centrifugalpumps (e.g., unmodified pumps). In this usage, the centrifugal pump can(but does not necessarily) provide both pump and mixing function. Whilea single such pump can be used, it can be advantageous to use aplurality of pumps, in which at least one pump is oriented as a forwardacting pump and at least one pump is oriented as a reverse acting pump.These centrifugal pumps should be configured so that there is a netforward flow. Such forward flow can be maintained, for example, by usingan independent pump of any appropriate type that has sufficient pressureand flow capacity to overcome the reverse action of any reverse actingcentrifugal pumps in the system. Alternatively centrifugal pumps can bearranged such that at least one of those pumps provides a net forwardflow, overcoming the sum of the reverse acting pumps. Such arrangementsare particularly suitable for the sequential processors described below.In such sequential systems, the pumps can, for example, be arranged inpairs with one pump forward acting and one pump reverse acting, suchthat the forward acting pump either equals or exceeds the action of thereverse acting pump. In cases where the forward action and reverseaction are equal, the forward flow can be provided by an earlier pump inthe system that provides a sufficient net forward pumping action.

In certain embodiments, the glycerol/biodiesel separator includes azonal flow-through separation tank (alone or in conjunction with otherseparation components), where the tank receives output from theprocessor mixer (e.g., as described above) and flow of reacted glyceridesolution through the tank establishes a mixing zone, a separation zone,and a glycerol accumulation zone. Accumulation of glycerol creates aglycerol/biodiesel interface within the tank, and glycerol below theinterface is removed. Such tank can include a secondary recycling drawtube located above and proximate to the glycerol-biodiesel interface,through which partially reacted glyceride solution is drawn.

In particular embodiments, the zonal flow-through separator tank has anupper mixing zone, a middle separation zone separated from said uppermixing zone by a baffle (e.g., a baffle plate), and a lower glycerolaccumulation zone; the baffle (e.g., baffle plate) includes a generallyhorizontal disk with a peripheral, downwardly projecting skirt; thegenerally horizontal disk is centrally located; the generally horizontaldisk is centrally located with a gap between the disk and the wall ofthe tank; the area of the generally horizontal disk is at least 60%,70%, 80%, 90%, 60-80%, 70-90%, 80-99% of the internal cross-sectionalarea of the tank.

In particular embodiments, the zonal flow-through separator tankincludes a first tank and a second tank, where the first tank provides amixed zone (e.g., in which partially reacted glyceride solution is mixedand produces reacted glyceride solution) and the second tank provides astagnant separation zone in which reacted glyceride solution is notsubstantially mixed such that glycerol separates from biodiesel.

Also in particular embodiments, the zonal flow-through separator tankincludes a tank of sufficient height and proportions that followinginjection of partially reacted glyceride solution in the top of saidtank there is created a substantially stable upper mixed zone, a centralstagnant zone, and a lower separated glycerol zone. Such tank dimensionsare generally tall and thin such that mixing at the top of the tank doesnot substantially mix a central portion so that separation can occur,and glycerol accumulates in the bottom portion. Such tank can include abiodiesel port located in the separation zone within a volume defined bya downwardly opening surface (e.g., a circular cylinder open at one end,an open-ended rectangle, a surface of rotation, and the like) where thedownwardly opening surface does not occupy such a large fraction of thecross-sectional area of that tank that it acts as a baffle thatsubstantially inhibits mixing below that surface (e.g., occupies lessthan 60%, 50%, 40%, 30%, 20%, 10% of the tank cross-sectional area.

In particular embodiments, the glycerol/biodiesel separator includes acyclone; the glycerol/biodiesel separator includes a centrifuge; theglycerol/biodiesel separator includes a cyclone and a flow-through zonalseparation tank; the glycerol/biodiesel separator includes a cyclone andat least one centrifuge; the glycerol/biodiesel separator includes aflow-through zonal separation tank and a centrifuge (e.g., where thecentrifuge receives output from the middle separation zone of the tank);the glycerol/biodiesel separator includes a plurality of centrifuges.

In certain embodiments of the processor, the biodiesel cleaner includesa washer; the biodiesel cleaner also includes a water/oil separator inwhich a centrifuge receives the biodiesel and water mixture from thewasher and separates the biodiesel from the water and water solublecomponents; at least 99.5% by volume of the water added in the washer isremoved from the biodiesel; the residual water in the biodiesel afterprocessing is less than 0.5%, 0.4%, 0.3%, or 0.2%; the biodiesel cleanerincludes a water mixer in which water is mixed with biodiesel to form abiodiesel/water mixture followed by a settling tank in which at least50%, 60%, 70%, 80%, 90%, or 95% of the water is removed from thebiodiesel/water mixture; the biodiesel cleaner includes a water mixer inwhich water is mixed with biodiesel to form a biodiesel/water mixturefollowed by a cyclone in which at least 50%, 60%, 70%, 80%, 90%, or 95%of the water is removed from the biodiesel/water mixture; the biodieselcleaner includes an ionically charged solid phase (e.g., particulate)medium (e.g., MAGNASOL®).

In certain embodiments, the processor further includes at least onealcohol separator where that separator removes alcohol from thebiodiesel or from the glycerol or from both; an alcohol separatorincludes an evaporative separator; the processor also includes anevaporative alcohol separator that removes alcohol from the biodieseland an evaporative alcohol separator that removes alcohol from theglycerol; an evaporative alcohol separator includes a vacuum evaporator;a vacuum evaporator includes at least one pressurized spray nozzle; anevaporative separator includes a heated vaporizer; a heated vaporizeralso includes at least one pressurized spray nozzle; a heated vaporizeralso incorporates a vacuum unit (e.g., a vacuum tank); a vacuum and/orheated vaporizer is linked with a condenser; an alcohol separatorincludes a nanofiltration unit.

In certain embodiments, the processor also includes an oil heater beforethe processor mixer; mixing of oil in the processor mixer causes atleast a 0.1, 0.2, 0.5, 1.0, 2.0, 5.0, 10.0 degree Celsius rise in thetemperature of the glyceride solution; the processor is capable ofprocessing at least 10, 20, 30, 40, 50, 80, 100, 200, or 400 liters perminute of glyceride solution; the processor includes a heated vaporizer(e.g., for vaporization of alcohol from biodiesel or glycerol, or forvaporization of water from biodiesel, or for distillation of glycerol)connected with a heat exchanger in which heat is recovered from thematerial heated in said vaporizer and used to heat a glyceride solution(e.g., an initial feedstock glyceride solution); the processor includesan alcohol recover unit; an alcohol recovery unit includes a vaporizer(e.g., heat and/or vacuum vaporizer) and may include a condenser; analcohol recovery unit includes a nanofiltration unit.

A related aspect concerns a continuous flow separation tank forseparation of components of a liquid mixture that form separate phases.The tank defines a liquid-containing volume, and thus includes acontainer that has sides, and a closed bottom. The tank also includes abaffle such as a generally horizontal baffle plate (e.g., in the centralportion of the container or around the periphery), a low density liquiddraw tube located below and proximate to (close to) the baffle plate;and a high density liquid draw tube located proximate to the lowerinternal terminus of the bottom.

In advantageous embodiments, the baffle plate is configured such thatthe plate inhibits fluid currents transferring from the mixing zone tothe separation zone. Removal of biodiesel and/or glycerol from below thebaffle plate will cause a limited current as reacted glyceride solutionfrom the mixing zone moves into the separation zone to replace thewithdrawn fluid. Preferably, this current is localized and separatedfrom the biodiesel draw tube (biodiesel port), so that the downward flowof replacement fluid is not directed toward that tube opening. Insteadthe replacement fluid is directed toward the glycerol biodieselinterface, so that biodiesel rises and/or moves laterally toward thebiodiesel draw tube opening while the glycerol continues to sink towardthe interface and adds to the separated glycerol. Thus, the biodieseldraw tube opening is placed so that fluid drawn through that tube isenhanced in biodiesel content without the long settling times requiredfor non-partitioned tanks.

In particular embodiments, the bottom includes an inverted cone section,a generally hemispherical section; an arcuate section, a reduceddiameter section.

In certain embodiments, the baffle includes a generally horizontalplate. Such baffle plate preferably includes at least a portion that isnot perforated. In certain embodiments, the baffle also includes agenerally vertical skirt surrounding an area defining a downwardlyopening cavity.

Instead of a generally horizontal plate, the baffle can be of othershapes that similarly create an upwelling or lateral migration volume,e.g., creates a downward opening cavity. For example, the baffle may beor include a cone, inverted hemisphere, inverted parabolic surface,inverted arcuate surface, or other downward opening curved surface ofrotation. In such cases in which at least a portion of the baffle and/orother surface define a downwardly opening cavity (i.e., defining anupwelling volume), the biodiesel draw tube is typically located abovethe lower edge of the surface, preferably near the top of the volume.Likewise the baffle may include a perforated surface and anon-perforated, downward-opening surface that is integrated with orlocated below that perforated surface.

In certain embodiments, the separation tank includes an intermediatedraw tube located above and proximate to the interface between thephases formed from the liquid mixture; the sides of the tank include orare in the form of a hollow, generally circular cylinder; the baffleplate includes a horizontal plate portion with a downwardly projectingskirt, e.g., a peripheral skirt; the area of horizontal plate portion isat least 60%, 70%, 80%, 90%, 95% of the horizontal cross-sectional areaof the tank at the location of the plate portion; the tank has a liquidcapacity of at least 1000, 2000, 3000, 5000, 10,000, 20,000, 40,000liters.

Another related aspect concerns a high turbulence flow-through processormixer that includes a fluid cavity with proximate opposing surfaces.Those opposing surfaces include projections, and at least one ofopposing surfaces rotates during use such that there is a relativevelocity between said surfaces (the opposing surfaces maycounter-rotate).

In certain embodiments of the processor mixer, the first projections andsecond projections bypass during rotation.

In certain embodiments, the processor includes a hollow outer housingthat includes an inner surface that has a plurality of firstprojections, and a proximate spaced apart inner body that has an outersurface that has a plurality of second projections, where the outerhousing and the inner body rotate relative to each other; the outerhousing includes an inner first cylindrical surface and the inner bodyincludes an outer second cylindrical surface, where the first and secondcylindrical surfaces are separated by an annular gap, and the relativerotation is about a common longitudinal cylindrical axis; the secondcylindrical surface is rotated and the first cylindrical surface isfixed; the relative velocity of the first and second cylindricalsurfaces is at least 2, 5, 10, 20, 30, 40, 50 meters per second (m/s) oris in a velocity range defined by taking any two different specifiedvelocity values as endpoints of the range; at least some of saidprojections include a substantially flat trailing edge surface havingsharp corners and oriented substantially perpendicular to the rotationdirection; at least some of the projections include a substantially flatleading edge with sharp corners; at least some of said projectionsinclude a tapering trailing surface, e.g., with a flat, curved, orobtuse angled leading surface.

In certain embodiments, the processor mixer includes a housing and agenerally circular rotor therein having a first face and a second face,in which the rotor includes a first set of projections on at least oneof the first and second faces and the housing includes a second set ofprojections on an inner surface proximate to the rotor face that has thefirst set of projections; the first set of projections includes or isessentially a set of vanes (e.g., vanes of the type typically used incentrifugal liquid pumps); the vanes include a set of concentric gaps,and the second set of projections include a matching set of concentricrings of projections that fit within those gaps; the vanes also includeat least one groove in their distal ends (i.e., at the periphery of therotor) and the housing also includes a third set of projections on theinner housing surface proximate to those distal ends, where the thirdset of projections project into the groove; wherein rotation of therotor is driven by a central shaft driven by an external power unit;rotation of the rotor is magnetically coupled to an external power unit.

Another related aspect concerns a method for processing a glyceridesolution to produce lower alkyl fatty acid esters by continuouslyprocessing a glyceride solution in a processor mixer as described hereinto produce a fatty acid alkyl ester solution, and separating glycerolfrom the lower alkyl fatty acid ester solution, and/or by using a zonalflow-through separator tank as described herein to effect suchseparation. The method can also include the use of other components andsteps as described for biodiesel production.

In another related aspect the invention provides a method for modulatingoutput from a biodiesel processor by altering the number and/orselection of processor mixers operating in a scalable biodieselprocessor as described herein. Such modulation can be an increase inoutput by addition of operation of a processor mixer in an operatingbiodiesel processor and/or by substituting a higher capacity processormixer for a lower capacity processor mixer. Conversely, such modulationcan be a decrease in output by removal of a processor mixer fromoperation while leaving at least one operating processor mixer and/or bysubstituting a lower capacity processor mixer for a higher capacityprocessor mixer.

Yet another related aspect concerns a method of producing a lower alkylfatty acid ester solution from a glyceride solution by using asequentially linked plurality of processor units, e.g., in a system asdescribed above, separating glycerol from lower alkyl fatty acid estersin the glycerol separator to produce a lower alkyl fatty acid estersolution, and cleaning said lower alkyl fatty acid ester solution insaid biodiesel cleaner.

In particular embodiments, the method also includes the use of analcohol recovery unit, e.g., an alcohol recovery unit that includes anevaporator and condenser or a nanofiltration unit separating glycerolfrom the alcohol; alcohol recovered in the alcohol recovery unit isrecycled through the processing system.

Another aspect concerns a method for flow-through processing of aglyceride solution to produce a fatty acid alkyl ester solution bycontinuously mixing the glyceride solution in a processor mixer (e.g., aflow-through high turbulence mixer); extending the reaction in aseparation tank; separately removing glycerol, fatty acid alkyl estersolution, and partially reacted glyceride solution from said separationtank; and reprocessing the removed partially reacted glyceride solutiontogether with additional unreacted glyceride solution through theprocessor mixer and separation tank.

In particular embodiments, the processor mixer and separation tank areas described herein. The system utilized in this method can also includeadditional components and steps for biodiesel processing, e.g., asdescribed herein.

Another aspect involves a method for separating solution components of aliquid mixture in a biodiesel/glycerol solution where the liquid mixtureforms two different phases on standing by injecting partially reactedglyceride solution into a separation tank wherein the tank includes aclosed top, a cylindrical central portion, a closed, reducedcross-sectional area bottom portion, an inlet injection tube proximateto the top, a baffle plate in the central portion, a first draw tubebelow and proximate to the baffle plate, a glycerol phase detectorfunctionally connected to a valved drain tube proximate to the lowerinterior terminus of the lower portion; extracting glycerol from thebottom of the tank through the valved drain tube, and extracting fattyacid alkyl ester solution from a region in the tank below and proximateto the baffle plate.

The tank may be as described for a zonal separation tank containing abaffle plate as described herein.

The method can also include extracting partially reacted glyceridesolution from above and proximate to a glycerol/oil interface in thetank through a second draw tube.

The invention, in another aspect, also provides a method for enhancingthe extent of reaction in a biodiesel processor including the continuousprocess of mixing unreacted glyceride solution with a C1-C3 primaryalcohol and a base catalyst (or solution of a lower alkoxide in a C1-C3primary alcohol) through a high turbulence processor mixer to form afirst mixture containing glycerol and biodiesel, separating biodieselfrom glycerol in a separation tank, removing biodiesel and glycerol fromthe separation tank, and removing and mixing partially reacted glyceridesolution from the separator tank with unreacted glyceride solution toform a second mixture, passing the resulting second mixture through thehigh intensity processor mixer together with additional first mixture,passing the reprocessed second mixture combined with first mixturethrough the separation tank, and continuously repeating the process.

The invention further provides a method for enhancing the reaction levelof alcohol in a biodiesel processor. The method involves use of aflow-through biodiesel processor and includes continuously separating afirst glycerol/alcohol mixture containing un-reacted alcohol andcatalyst from biodiesel, mixing that glycerol/alcohol mixture containingun-reacted alcohol and catalyst with un-reacted (or less-reacted)glyceride solution forming a recycling reaction mixture, and processingthe secondary reaction mixture through the processor.

In general, the method involves taking an alcohol-rich (e.g., methanol-or ethanol-rich) glycerol fraction from a later stage in a multi-stepbiodiesel production process and utilizing that fraction in an earlierstep, either alone or with enrichment with fresh methanol and/orcatalyst. The result is that at least most of the alcohol can be reactedwithout requiring separation of the alcohol from the glycerol and reuseof the alcohol. Such recycling can be performed multiple times in aprocess. Advantageously, in the last reaction step or set of steps, thealcohol-depleted glycerol can be separated from the reacted glyceridesolution and fresh alcohol and/or catalyst added to drive the reactionto completion.

Thus, in particular embodiments, the biodiesel processor includes atleast 2 sequentially linked processor mixer and separator pairs. The atleast 2 pairs includes at least one first pair and at least one secondpair, and the method includes removing a second glycerol/alcohol mixturefrom a separator in the first pair, adding fresh alcohol and catalyst topartially reacted glyceride solution from a first pair forming asecondary reaction mixture and processing that secondary reactionmixture through a second pair, removing the first glycerol/alcoholmixture containing un-reacted alcohol and catalyst from a separator inthe second pair and mixing with un-reacted glyceride solution to formthe recycling reaction mixture.

Another aspect of the invention concerns a method for operating abiodiesel processor business. The method involves a supplier providing abiodiesel processor to a third party along with a grant of rights tooperate the biodiesel processor. The grant of rights to operate thebiodiesel processor is in conjunction with an agreement in which the3^(rd) party agrees to pay a use fee to the supplier. The method mayalso include an agreement in which the supplier services the processorand/or agrees to purchase all or part of the production from theprocessor.

In certain embodiments, the processor is a transportable processor; theprocessor is installed within a closed container, e.g., a shippingcontainer; the contents of the container are not accessible to the3^(rd) party; the processor is one described herein; the processor is asequential processor; the processor is a scalable processor; theprocessor includes both scalable and sequential features.

Additional embodiments will be apparent from the Detailed Descriptionand from the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically shows an exemplary biodiesel processor system thatincludes a processor mixer and a flow-through separation tank.Additional optional processor mixers are also shown; when included suchadditional processor mixers can make the system into a scalableprocessor.

FIG. 2 shows a longitudinal cross-section of an exemplary cylindricaldesign high turbulence processor mixer useful in the present systems.

FIG. 3 shows a cross-section of an exemplary radial design highturbulence processor mixer useful in the present systems, where thecross-section is taken along a plane that includes the axis of rotationof the rotor.

FIG. 4 shows a cross-section of the processor mixer shown in FIG. 3,where the cross-section is taken perpendicular to the axis of rotationof the rotor and just above the surface of the rotor, thereby creating aplan view of the rotor surface.

FIG. 5 schematically shows the processor mixer and reaction/separationportion of a processor system that uses sequential processor mixers withglycerol separation between processor mixers.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention addresses the need for efficient production ofbiodiesel by providing continuous flow biodiesel processors (i.e.,processing systems). In many systems, biodiesel is produced using atransesterification reaction to convert glycerides, especiallytriglycerides, to lower alkyl esters of the constituent fatty acids andglycerol. Usually the reaction is catalyzed, usually either acid or basecatalysis. Of these, basic catalysis is used more often, e.g., usingNaOH or KOH. The present processors generally include a high turbulenceprocessor mixer followed by a flow-through glycerol/biodiesel separator,such as a flow-through zonal tank separator.

Such processors can be configured in a number of different ways,including a single processor mixer linked with a singleglycerol/biodiesel separator, multiple processor mixers linked inparallel with each processor mixer feeding to a common separator or to aseparate separator, and multiple sequential (i.e., series-linked)processor mixers which may have glycerol/biodiesel separators operatingfollowing each processor mixer or may have a separator after several orall of the processor mixers.

A number of options for different configurations and options foradditional system components are described below.

In order to more clearly explain the present invention, the followingterms have the meanings as specified.

The term “alcohol” refers to a compound that consists of an alkyl groupbearing a single hydroxyl group, especially a primary hydroxyl group,i.e., a primary alcohol. Examples include methanol and ethanol. Thus, inthe context of a biodiesel processor, the term “alcohol separator”refers to a component or set of components that separates alcohol fromother components in a particular solution or mixture. The alcoholseparator may substantially purify the alcohol or may co-separate thealcohol along with one or more other species (e.g., separate the alcoholwith catalyst species from glycerol or from biodiesel).

As used herein in connection with biodiesel production, the terms “alkylesters”, “alkyl fatty acid esters”, and “fatty acid alkyl esters” referto alkyl esters of fatty acids, e.g., lower alkyl esters (i.e., “loweralkyl fatty acid esters”) where the lower alkyl moiety has 1-6, (or innarrower embodiments 1-4, 1-3, or 1-2) carbon atoms. Examples includemethyl, ethyl, propyl, isopropyl, butyl, sec-butyl, tert-butyl esters,but especially methyl or ethyl esters. Thus, the term “lower alkyl fattyacid ester solution” refers to a solution that is predominantly composedof such esters, but may contain other components, e.g., contaminants.

The term “annular” is used to refer to a ring-like shape or space.

In the context of the present zonal flow-through separation tanks, theterm “baffle plate” refers to a partial, usually generally horizontal,barrier within the tank that sufficiently inhibits bulk movement ofliquid below the baffle plate such that bulk mixing above the baffleplate is not substantially transmitted to liquid below the plate. Moregenerally, in the context of such tanks, the term “baffle” refers to anystructure that inhibits bulk movement of liquid in the tank such thatthe baffle creates volume zones having separate mixing regimes. Inconnection with baffle plates, a “downwardly projecting skirt” refers toa generally vertically oriented member that attaches to the generallyhorizontal barrier at its upper end and together with the baffle platedefines a downwardly opening cavity.

As used herein, the term “biodiesel” refers to a solution of lower alkylesters of fatty acids. Low amounts of other components may be present,such as low levels of glycerides, free fatty acids, salts of fattyacids, glycerol, alcohol, and/or water.

The term “biodiesel processor” is used herein to refer to a combinationreaction and separation system adapted for producing lower alkyl fattyacid esters from glycerides, and separating the reaction products.Additional components may also be included, e.g., pumps, biodieselwasher, glycerol distiller, and the like.

The terms “biodiesel cleaner” and “cleaner” are used herein to refer toa component or system which removes contaminants from a biodieselsolution (lower alkyl fatty acid ester solution), such as residualalcohol, soaps, catalyst, and the like. Such a cleaner may include awasher.

The term “centrifuge” is used in its conventional sense to refer to amachine for separating materials of different density, e.g., liquidsthat form separate phases or particles from a liquid, using high speedrotation of the fluid, especially in conjunction with rotatingmechanical portions of the machine.

In the context of separators, the terms “cyclone” and “cyclonicseparator” refer to a device in which cyclonic motion of a fluid producea low force separation of components having different densities.

As used herein, unless expressly modified the terms “cylinder” and“cylindrical” refer to a right circular cylinder. The terms “cylinderaxis”, “cylindrical axis” and “longitudinal cylindrical axis” refer tothe central axis of the cylinder.

The terms “flow-through” and “continuous flow” mean that in normaloperation, a fluid flows continuously through the referenced system orcomponent without substantial interruption for the duration of theperiod of operation, such that the output rate is essentially equal tothe input rate for the referenced system or component duringsteady-state operation.

In the context of the present systems and components thereof, the term“functionally linked” indicates that the cited components operatetogether in the processing of the oil, e.g., that the oil beingprocessed progresses between the components. Unless expressly indicated,it does not require that the components are directly connected to eachother (i.e., connected with no intervening component).

The term “glyceride” is used to refer to esters of glycerol(propane-1,2,3-triol) with fatty acids. Such glycerides include mono-,di-, and tri-glycerides (i.e., mono-, di-, and tri-O-acylglycerol).

The term “glyceride solution” refers to a solution that containspredominantly mono-, di-, and tri-glycerides. Usually such a solutioncontains at least 80, 90, 95, 96, 97, 98, 99, or 99.5% of suchglycerides. Such solution may contain low levels of other components,e.g., free fatty acids, waxes, soaps. Typical glyceride solutions usefulin biodiesel processing include any of a variety of vegetable oils suchas canola, soybean, corn, and rapeseed oils. In the present context,“partially reacted glyceride solution” and “partially reacted reactionmixture” refer to a glyceride solution that has been reacted with otherreactants in a biodiesel production reaction but may still retainsignificant un-reacted glycerides, e.g., at least 10% glycerides byvolume, and has not been cleaned. Similarly, the term “reacted glyceridesolution” refers to a glyceride solution that has been reacted withother reactants in a biodiesel production reaction, which has not beencleaned and which may, but need not, still include significantun-reacted glycerides.

The terms “glycerol/biodiesel interface” and “glycerol/reacted glyceridesolution interface” refer to a bulk liquid phase interface betweenglycerol and an oil phase in biodiesel processor, e.g., in a separatortank.

In the context of the present biodiesel processors, the term“glycerol/biodiesel separator” refers to a device or combination ofdevices that substantially separates glycerol from an oil phase,especially biodiesel or a partially reacted glyceride solution. Examplesof such glycerol/biodiesel separators include tanks, cyclones, andcentrifuges.

In the context of oil mixing, the term “high turbulence” means a mixingregime in which small scale mixing is dominant (over bulk transport).Generally the Reynolds number for such regimes will be at or above10,000, usually at or above 100,000 or at or above 500,000. In manycases, the turbulence will be such that the turbulence vortices are ofsufficiently small scale that viscous heating is substantial, e.g.,results in heating in a high turbulence biodiesel processor mixer duringnormal operating conditions of at least 0.1 degree C.

In the context of the present processor mixers, the term “inner body”refers to a separate three dimension object located within a chamber ofan outer portion (e.g., a housing).

In the present context, the term “ionically charged solid phasematerial” refers to a solid phase material that carries charged moietiesthat remains as a solid phase when contacted with or suspended in aliquid of interest, e.g., in biodiesel and/or other oils. Thus, the term“ionically charged particulate medium” is an ionically charged solidphase material” that is in particulate form.

In the context of the present processors, the term “housing” refers to aprotective cover designed to contain or support a mechanical component,and in particular to contain an inner body where the housing and innerbody rotate relative to each other. Such a housing has an inner cavity,i.e., is hollow.

As used herein, the term “nanofiltration” refers to filtration in whichthe retention size cut-off is small molecule size, e.g., with molecularweight cut-offs from about 50 to about 1000 Daltons. This isdistinguished from microfiltration, ultrafiltration, and reverse osmosis(RO).

In the present context, unless expressly indicated to the contrary, theterm “oil” or “oil phase” refers to a liquid that is predominantly madeup of compounds that contain long chain fatty acids, e.g., glycerides,free fatty acids, and esters of fatty acids.

In the context of the present of the present processors, the term “pipe”refers to a flow channel that has a length of at least 5 times theinternal diameter (or average linear dimension normal to the flow path(cross-dimension) for channels that are not circular in cross-section).More often, the length will be at least 10, 20, 40, 60, 80, or 100 timesthe average cross-dimension. The cross-sectional shape may be any thatallows flow of the relevant fluid (e.g., glyceride solution orbiodiesel).

As used herein in the context of movement of fluid through a channel(e.g., a pipe, tank, trough, or the like), the term “plug flow” meansapproximately plug flow, not ideal plug flow. That is, the flow proceedswith roughly the same velocity across the cross-section of the channel,but typically has mixing across the channel. For example, the

In the context of constituents of a liquid solution or mixture, the term“polar components” refers to chemical species in the solution or mixturethat are polar (i.e., have a substantial dipole moment) or charged(e.g., a sodium ion).

The term “processor mixer” is used to refer to a component of abiodiesel processor system in which a glyceride solution is mixedtogether with additional reactants. A “high turbulence processor mixer”or “high intensity processor mixer” is one in which the mixing occursunder conditions of high turbulence, e.g., Reynolds number at or above10,000. Further, a “high turbulence flow-through processor mixer” is ahigh turbulence processor mixer which normally operates in aflow-through manner such that the fluid flow rate into the mixer isessentially equal to the fluid flow rate out of the mixer.

In connection with the present processor mixers, the term “projections”refer to convex shape that juts out from a surface, e.g., a housingsurface, inner body surface, or rotor face. In relation to suchprojections from surfaces of processor mixers where opposing surfaceshave relative velocity, the term “bypass” means that the tips ofprojections from one surface extend past the tips of projections fromthe other surface. In connection with the shapes of such projections,the terms “flat trailing surface” and “substantially flat trailingsurface” means that the portion at the back of the projection relativeto the rotation direction is substantially flat although it may haveminor curvatures, angles, or other deviations from flatness. Forexample, unless expressly indicated to the contrary, deviations fromflatness of less than 1, 2, 5, or 10% of the width of the surface areregarded as substantially flat. Similarly, in connection with theorientation of projections, the term “substantially perpendicular” meansthat the specified line is approximately perpendicular to a referenceline. Unless expressly indicated to the contrary, an angle of 90±20degrees (e.g., 90±15, 90±10, 90±5 degrees) is regarded as substantiallyperpendicular. Likewise, the term “tapering trailing surface” means thatthe portion at the back of the projection has significant extension,e.g., an angular or curved extension, such that it becomes progressivelynarrower toward its trailing terminus. For example, a projection mayhave a triangular cross-section with the base forming the leading edgeand an acute angle in the trailing direction. Such extension may, forexample, be at least 50, 100, 150, or 200% of the maximum width of theprojection.

In relation to the present two cylinder processor mixers, the terms“relative rotation rate” and “relative velocity” refer to a rotationrate or rotational velocity defined by taking the rotation rate of oneof the cylinders as zero and determining the velocity of the othercylinder using the fixed cylinder frame of reference. Thus, for example,if both cylinders were rotating at the same angular velocity, therelative rotation rate would be zero. Likewise, if each cylinder wererotating at the same rotational speed in opposite directions, therelative rotation rate would be double the rotation rate of eithercylinder.

In the context of the present systems, the term “scalable” means thatthe system is configured such that it includes multiple processor mixerswhich can individually be operated or removed from operation withoutpreventing operation of other processor mixers in the system. Thisallows the biodiesel output rate of the system to be varied over a widerange.

In the context of a separator tank in the present invention, the terms“secondary recycling draw tube” and “recycling draw tube” and the likerefer to a tube or port in a glycerol/biodiesel zonal separation tank,where the tube is located above the glycerol/biodiesel interface andbelow the biodiesel draw tube (biodiesel port) such that partiallyreacted glyceride solution, if present, can be drawn through the tube.

As used in connection with a biodiesel production processor, the term“separator” refers to a component or set of components thatsubstantially isolates or purifies one or more constituent species froma mixture, especially from a liquid mixture. For example, such aseparator may remove one or more species from a bulk liquid or mayseparate a bulk liquid into two or more derivative fluids havingsignificantly different compositions. Thus, an “evaporative separator”utilizes evaporation (i.e., phase change from liquid to vapor) of one ormore constituent species as a significant element in the separation.Similarly, a “vacuum separator” or “vacuum evaporator” utilizes avacuum, i.e., a pressure significantly lower than normal atmosphericpressure, as a significant element in the separation, e.g., toaccelerate the transition of a constituent species from liquid to vapor.A “heat vaporizer” or “heated vaporizer” utilizes heat energy as asignificant element in the separation, particularly to accelerate thetransition from liquid to vapor of a constituent species. Also in thecontext of phase transition between vapor and liquid, the term“condenser” refers to a component or set of components in which thetemperature of a vapor phase is reduced, such that a significantproportion of at least one species in the vapor transitions to a liquid.Also in the context of separators in a biodiesel processor, the term“pressurized spray nozzle” is used to refer to a device that includes atleast one small orifice through which a liquid is directed underpressure such that a spray of small droplets is formed, e.g., an aerosolof liquid droplets.

In the context of a biodiesel processor system, the term “separatortank” refers to a tank configured such that when the tank is filled witha solution containing at least two liquids that will separate onstanding, the separation will occur, and the tank includes outletsadapted for removal of at least two different fractions. A “flow-throughseparator tank” is one in which the separation occurs while essentiallycontinuous flow of material into and out of the tank is maintained atessentially equal rates, i.e., steady-state.

In reference to projections in the present processor mixers, the term“set” means one or more. Usually such set is a plurality, e.g., at least2, 5, 10, 20, or more.

In the context of the present processor mixers that include rotors, theterm “vane” refers to any of several usually relatively thin, rigid,flat or curved surfaces radially mounted along an axis, as a blade in aturbine or centrifugal pump, that is turned by or used to turn a fluid.Such vanes may be attached to a disk on one or both sides, or may belocated between and attached to two disks.

In a biodiesel production system, the term “washer” refers to componentsthat together introduce water (or other polar solvent) into a biodieselsolution thereby removing water soluble (or soluble in the utilizedpolar solvent) components (e.g., polar (including charged) components)from the biodiesel, and may include components that removed the addedwater. In such a washer, a “water mixer” is a component or set ofcomponents that adds water to the biodiesel or other oil in a mannerthat substantial mixing of water with the oil occurs.

In the context of liquid mixtures and solutions in a biodieselproduction system, the term “water soluble” indicates that the molecularor ionic species in question has substantial solubility in water at theoperating temperature of the system. Such solubility is highlypreferably significantly greater in water than in biodiesel, e.g., atleast 2× (or at least 5×, 10×, 50×, or 100×) the solubility inbiodiesel.

The terms “zonal separation tank”, “zonal flow-through separation tank”,and “flow-through zonal separation tank” are used to mean a separationtank that is designed such that during flow-through operation withsolution reacted for producing biodiesel from glyceride solution, 3distinct zones will be established within the tank: 1) mixing zone, 2)separation zone, and 3) glycerol accumulation zone. In certainembodiments, the separation zone is set off from the mixing zone by abaffle plate, such that there is a relatively stagnant zone below thebaffle, and a mixed zone above the baffle. In the context of operationof such tanks, the term “mixing zone” refers to a volume of the tank inwhich the fluid is continuously mixed. The term “separation zone” refersto a volume of the tank in which mixing is sufficiently small that phaseseparation between glycerol and the oil (e.g., reacted glyceridesolution or biodiesel) will occur and glycerol will migrate to aglycerol accumulation zone under the influence of gravity. The term“glycerol accumulation zone” refers to a volume of the tank in whichglycerol separating from the reacted glyceride solution accumulatesduring phase separation and in response to gravity.

Also in the context of mixing in zonal separation tanks, the terms“stagnant” and “not substantially mixed” indicate that bulk liquidmovement within the particular region of the tank is sufficiently lowthat such movement allows significant separation of glycerol frombiodiesel where the glycerol fraction is at least 0.1 g/cm³ denser thanthe biodiesel fraction.

A. Reagent Supply

The present systems and methods generally utilize conventionalchemistries for production of lower alkyl fatty acid ester biodieselsfrom glyceride solution feedstocks. In most cases, the reaction utilizesa lower primary alcohol, e.g., methanol or ethanol, with a basiccatalyst, e.g., NaOH or KOH, or a direct solution of a lower alkoxide ina lower alcohol, e.g., sodium methoxide in methanol (i.e., methanolicsodium methoxide). Other variations on the reaction chemistry can beused, e.g., variations as described in the art, such as acid catalyzedreactions, processes that combine acid catalyzed and base catalyzedreactions, the use of other catalysts, and high pressure reactions(catalyzed or non-catalyzed).

The glyceride solution can come from any of a variety of sources. Inmany cases, the source is a vegetable oil, e.g., from oil seed (forexample, soybean, corn, linseed, peanut, sunflower, castor bean, orcanola oil) or palm or coconut oil. Animal fats and/or waste oils canalso be used. Certain sources may need early stage treatment to reducecontaminants and/or to reduce the content of free fatty acids.

Thus, the present systems and methods utilize liquid reaction mixturesthat generally include a glyceride solution feedstock that is combinedwith a lower alkyl group donor species (e.g., a lower primarily alcoholsuch as methanol or ethanol) and usually a catalyst (e.g., NaOH, KOH,sodium methoxide, or potassium methoxide for base catalysis). Thefeedstock can be pumped or transported by gravity or other force from areservoir into a processor mixer. The other reagents can be mixed intothe glyceride solution in a variety of ways, e.g., using an in-linemixer, using a rapidly stirred mixing tank, using injection into aprocessor mixer.

In most cases, the glyceride solution, or the reaction mixture will beheated prior to entry into a processor mixer, e.g., to about 60-65degrees C. Such heating can be accomplished using various heatingmethods, for example, directly using a heater, e.g., an in-line heater,or using a heat exchanger, e.g., using heat recovered from a heatvaporization process.

Heated glyceride solution or reaction mixture is directed to a processormixer, e.g., a high turbulence processor mixer as described below.

B. High Turbulence Processor Mixers

In the present systems, a processor mixer is a device in which thereaction mixture is intimately mixed, preferably vigorously (which cangenerate an emulsion). The present systems can incorporate any of avariety of different processor mixers. In such mixers the esterificationreaction is initiated, and in some cases proceeds substantially duringpassage through the processor mixer. A variety of mixers described inother publications can be used. In addition, advantageously highturbulence processor mixers as described herein can be used in thepresent systems and methods.

In order to maximize the reaction, it is desirable to dramaticallyincrease the surface area of the phase interface between the non-polarglyceride phase and the polar methanol phase. In advantageousembodiments of the present invention, this is accomplished through veryintense physical mixing. To ensure that highly effective mixing hasoccurred, the mixing can be taken to a level such that appreciableviscous heating occurs during passage of the reaction mixture throughthe processor mixer, e.g., at least a 0.1 or 0.5 degree Celsius rise intemperature during passage through the mixer (or even a greatertemperature rise, for example, at least 1.0, 2.0, 3.0, 4.0, 5.0, 6.0,10.0 Celsius or greater temperature rise). Such intense mixingcontributes additional heat energy to the system which can increase thereaction rate, and may also create local high pressure areas in whichthe reaction rate can be locally increased. While such high intensity,high turbulence mixing is advantageous, excessive mixing can be wastefulof mixing energy.

Two exemplary types of high intensity processor mixers are describedherein, but variants and other designs can also be used. One design typeutilizes an outer housing with an inner body, with a fluid space betweenthe two. The housing and/or the inner body is rotated such that there isrelative rotation between the housing and the inner body. The bulk fluidflow-through the processor mixer occurs through the fluid spacegenerally parallel to the axis of rotation of the housing and/or theinner body. For example, the housing can have an inner surface in theshape of a cylinder, the inner body is a smaller cylinder such thatthere is a space (e.g., an annular space) between the cylinders, and thetwo cylinders have parallel longitudinal axes (e.g., a commonlongitudinal) cylinder axis. The longitudinal axes (e.g., commoncylinder axis) are also the rotation axes. The overall direction of bulkflow of the reaction mixture is parallel to the axis of rotation. Thatis, the glyceride solution flows into one end of the space between thecylinders and exits from the other end, e.g., through apertures in thehousing leading to suitable tubes or pipes. The inner and outercylinders include projections that project into that annular space andmay bypass. The relative rotation rate is typically sufficiently highthat the speed of the projections passing through the reaction mixturecreates highly turbulent conditions in the reaction mixture.

While most such processor mixers are selected to have cylindricalshapes, other shapes can also be used. In such cases, the inner andouter surface projections should pass sufficiently closely to each otherthat high turbulence conditions are created in the reaction mixture. Onesuch variant would use an outer cylinder, with a polygonal inner body,e.g., a square, pentagonal, or hexagonal body. The inner body can havesmall projections and/or the polygon corners may provide theprojections.

A second type of exemplary design is a processor mixer design that is acentrifugal (or radial) design analogous to a conventional centrifugalpump for liquids. Similar to such pumps, such a mixer includes a housingthat has a circular chamber within it (often a flattened circularchamber). Within that circular chamber is located a disk-shaped rotorthat includes vanes (or other shape projections) on at least onesurface. Opposing projections are located on the facing housing surface.In operation, the fluid enters the housing cavity centrally, typicallyalong the rotational axis of the rotor, and exits the pump through anopening(s) in the periphery of the housing. In most cases, the exitopening is essentially tangential to the periphery. The projections onthe rotor and the projections on the housing are located and distributedsuch that motion imparted to the liquid by the rotor is countered by theprojections on the housing.

In some designs, the rotor includes vanes on one surface of the rotor,and the vanes have a concentric series of circular grooves, which may bepartial or cut fully to the rotor backing disk. The projections on thefacing surface of the housing are distributed in rings such that theycan project into the rotor vane grooves. In operation the fluid entersthe cavity through the housing centrally to the rotor. The rotatingrotor causes the fluid to be accelerated forward and outward. Thatmotion is then interrupted by the first ring of housing projections,significantly slowing outward migration of the fluid and causing intensemixing. As the fluid passes the first ring of housing projections, thenext section of vane again accelerates the fluid until it encounters thenext ring of housing projections. The process is repeated until thefluid passes the last ring of projections, and passes out through theperipheral opening. An additional groove and corresponding projectionscan be present in the distal tips of the vanes and the inner peripheralsurface of the housing respectively. Processor mixers of this type canbe designed to function as combination processor mixer/pump.

In one alternative, the mixer may have counter-rotating rotors withopposing projections on each rotor. The projections can constitutebypassing rings of projections, closely fitting vanes, or otherconfigurations. The projections can be distributed such that they do notimpart a net outward fluid flow. In such designs, the fluid is movedthrough the processor mixer using an external pressure (e.g., from aseparate pump). Alternatively, the sets of projections can be sized,shaped, and distributed such that the net fluid motion is outward. Incertain embodiments of this design, the projections can be designed andconfigured such that the net velocity of the fluid causes the processormixer to also function as a pump.

Such intense mixing, e.g., using the present processor mixers, cancreate an emulsion, which may be an unstable emulsion. In this context,an “emulsion” is a suspension of small globules of one liquid in asecond liquid with which the first does not substantially mix, e.g., thepolar lower alkoxy components intimately mixed into the glyceridesolution.

The processor mixer size and mixture flow rate can be balanced toestablish a desired residence time for the fluid in the mixing zone ofthe mixer, e.g., a residence time of 1-5, 2-10, 5-20, 10-30, 20-40,30-60, 60-120 seconds.

Highly intense mixing may also be accomplished or facilitated usingultrasound agitation and/or passage of the glyceride/base/alcoholmixture through a small orifice under pressure (preferably a series ofsuch passages).

C. Biodiesel Separators, Including Flow-Through Separator Tanks

In biodiesel processors that utilize a processor mixer, the system alsogenerally includes a glycerol/biodiesel separator for separating thereaction products, glycerol and biodiesel (lower alkyl fatty acidesters). In most cases, such separators utilize a separation tank,cyclone, and/or centrifuge. Separator tanks are commonly used inbiodiesel processor systems to provide additional reaction time and toseparate the glycerol from the product esters and unreacted glycerides.In some cases, the solutions in such tanks are subjected to initial lowto moderate mixing, followed by a period of very little or no mixingduring which glycerol settles to the bottom leaving biodiesel as theupper phase. Such separation typically requires several hours to severaldays depending on the tank size and the degree of separation desired.However, such long separation times are undesirable because of thelimitations on processing capacity (or alternatively the need for manylarge tanks), as well as the potential for reversal of the reaction.

Thus, the present processors include efficient and rapid flow-throughseparators to separate glycerol from biodiesel (or partially processedglyceride solution). Certain of the present systems include separatortanks that efficiently separate the glycerol reaction product from thebiodiesel product and unreacted oil. In the present system, preferably aglycerol/biodiesel separator tank is used that is configured such thatthere are distinct zones. In the mixing (usually upper) zone,significant mixing of the solution occurs, in an intermediate separationzone there is little mixing such that separation can proceed, and in thebottom zone the glycerol collects. In preferred systems, as glycerolcollects, it is automatically drawn or drained off. Such draining of theglycerol can be controlled to prevent removal of biodiesel solution,e.g., by triggering the removal using a medium buoyancy float valve thatfloats in glycerol but not in oil.

The different zones can be controlled by internal tank structures. Forexample, the upper mixing zone can be created by the flow pressure anddirection of the incoming reaction mixture; the middle separation zonecan be delimited by a baffle at the bottom of the mixing zone and top ofthe separation zone; and the bottom glycerol accumulation zone includesa tapered or otherwise reduced cross-section portion facilitatingglycerol removal, and which also can reduce the bulk interface betweenthe glycerol layer and the oil layer.

As indicated, in such tanks, the bottom section can advantageously be areduced cross-sectional area portion, e.g., an inverted cone,hemisphere, arcuate section, a reduced cross-section cylinder or othercross-sectional shape with cross-sectional area reduced from the mainportion of the tank.

Such tank will incorporate an inlet for reacted glyceride solution(usually in the upper portion of the tank), a biodiesel draw tube(biodiesel port) (typically located in the separation zone), and aglycerol draw tube (glycerol port) in the glycerol accumulation zone(typically near the bottom). Additional ports or tubes may also beincorporated in a particular design. For example, a recycling draw tubemay be included, which may be located to satisfy the requirements of theparticular system. Examples of locations for recycling draw tubesincludes within the mixing zone, and in the separation zone (e.g., closeto but above the glycerol/biodiesel interface or high in the separationzone but below the biodiesel draw tube). The recycling draw tube is usedto supply a partial volume for reprocessing through a processor mixer.Such reprocessing can be used to increase the extent of conversion ofglycerides to biodiesel.

The glycerol draw tube is advantageously located in association with abiodiesel separator structure. Such a biodiesel separator structure canbe advantageously constructed such that counter-current migration ofbiodiesel is involved in movement of biodiesel to the glycerol drawtube. Such counter-current migration can be accomplished by using asurface that defines a downwardly opening cavity. The surface can be ofvarious shapes, e.g., downward opening cylinder, cone, hemisphere orother surface of revolution. The biodiesel draw tube is preferablylocated within the cavity defined by that surface, preferably at or nearthe top of that cavity.

The baffle may also be constructed in various ways and may be integratedwith the biodiesel separator structure. The baffle inhibits mixingcurrents from substantially extending from the mixing zone to theseparation zone, while permitting migration of reacted glyceridesolution into the separation zone. For example, the baffle may be aplate that blocks a substantial portion of the cross-section of the tank(e.g., a centrally located plate), a perforated plate covering the fullcross-section of the tank, or a set of vertical plate sections creatinga set of vertically oriented passages. The biodiesel separator structurecan be integrated with the baffle, e.g., a peripheral skirt or smallervertically oriented wall sections can be mounted on the lower surface ofa baffle plate thereby defining a downwardly opening cavity. Similarly,a peripheral plate can have a downwardly projecting skirt, againdefining a downwardly opening cavity. Alternatively the biodieselseparator may be a separate structure located below the baffle. Avariety of other such structures (alone or in combination) can also beutilized for the baffle and biodiesel separator structure.

A baffled tank can also be advantageously used in a batch operation.When a baffled tank is used in a batch operation, mixing throughout thetank is maintained by drawing from the glycerol and/or biodiesel portsand recirculating that fluid draw. As soon as the reaction has gone tocompletion, glycerol-free biodiesel can be drawn from the biodiesel port(the draw tube under the baffle) immediately after bringing the reactionto completion. This is because the biodiesel must travel slowly upwardto the draw tube, leaving behind the glycerol. As a result, it is notnecessary to allow the whole tank to settle before beginning to draw offbiodiesel, thereby saving time. Using a baffled tank in batch mode, theentire operation can be done using minimal electronics (ingredients canbe manually measured and added to the batch), and no centrifuges (waterwash would remove any residual glycerol). Thus, the invention alsoconcerns the process or method of biodiesel production using such a tankin batch mode.

In other cases, the zonal separation tank utilizes multiple tanks. Thereacted glyceride solution enters a mixing tank that typically provideslow to moderate mixing, e.g., sufficient to prevent, or at leastsubstantially slow, phase separation. After an interval of mixing, thereacted glyceride solution moves to a second tank in which the liquid issufficiently still so that mixing currents do not substantially affectthe glycerol/biodiesel separation rate. Such a tank may incorporate abaffle(s) (e.g., to quickly still currents associated with inlet flow)and/or biodiesel separator structures (e.g., as described above forbaffled tanks).

In yet other cases, a non-baffled tank is utilized that functions as azonal separation tank. Such tanks are relatively tall and thin such thatmixing in the upper section (the mixing zone) is dampened by viscousfriction before reaching the lower portions of the tank. As a result, aportion of the tank functions as a separation zone, and the bottom ofthe tank is the glycerol accumulation zone. Such tanks mayadvantageously incorporate a biodiesel separator structure (e.g., asdescribed above for zonal separation tanks that include a baffle).

As an alternative, or in conjunction with separator tanks and/orcentrifuges, cyclones may be used to provide a substantial separation ofglycerol from biodiesel. Thus, for example, a cyclone(s) may be used toprovide rapid initial separation removing most of the glycerol, withmore complete separation provided using a separation tank or centrifuge.Such rapid removal assists in preventing back reaction.

In other systems, one or more centrifuges can be used to rapidlyseparate glycerol and biodiesel. Such centrifuges may be incorporated ina system in various ways. For example, centrifuges may provide fullseparation function, or may be combined with separation tanks and/orcyclones. Thus, a tank may be used to provide initial separation, with acentrifuge(s) used to rapidly complete the separation. Alternatively, acyclone(s) may provide the initial separation, with the centrifuge(s)completing the separation.

D. Biodiesel Cleaner

A biodiesel production system will typically contain a system forcleaning the biodiesel phase, e.g., to remove residual glycerol,alcohol, and catalyst, following passage through a glycerol/biodieselseparator. Such cleaning can be accomplished using various methods andapparatus such as the following.

1. Phase Separation

A partial cleaning can be accomplished using a phase separation method.For example, the crude biodiesel solution can be allowed to separate fora substantial period of time in a tank and/or can be centrifuged. Suchtechniques can remove a large fraction of the residual glycerol andmethanol, but some of those materials will typically remain in solutionin the biodiesel phase. Therefore, for further cleaning it can bebeneficial to use one or more other methods as alternatives orsupplements.

2. Water Wash

A large proportion of polar contaminants can be removed using a waterwash. This is followed by removal of the water, e.g., through acombination of phase separation to remove most of the water (e.g., in atank, cyclone, and/or centrifuge) usually followed by evaporation (e.g.,as described below) to remove the remainder. Such water wash and waterremoval can be accomplished using methods conventional in biodieselprocessing. In some cases, it is desirable to use slightly acidifiedwater for the wash process.

In order to increase the fraction of water removed, it can be beneficialto use multiple centrifuges in series; in such series it may be desiredto have the final centrifugation be a high intensity centrifugation,e.g., about 1000×g or greater.

3. Solid Phase Adsorption

Residual contaminants can be removed using solid phase media that adsorbthe contaminants to be removed. Such a solid phase media can be mixed inthe solution and then settled and/or filtered out, or can be immobilized(e.g., in a column). A material used for such purposes is magnesiumsilicate, e.g., sold in a powdered form as MAGNASOL® (Ciba Corporation).The adsorbent can then be filtered out of the biodiesel, e.g., filteredat least through a 5 micron filter, or preferably with final filteringthrough a 1 micron filter. Such solid phase adsorption can be used asthe sole cleaning method, as the primary cleaning method with asupplementary second method, or as a supplement to washing.

4. Evaporative Methods

Other methods to remove contaminants include methods utilizingevaporation of at least the more volatile components, e.g., alcoholand/or water. Such evaporative methods can involve conventionaltechniques, e.g., vacuum evaporative method, with or without generationof aerosol and with or without use of heat. Likewise, the evaporativemethod may utilize heat, e.g., above the boiling point of the volatilecomponents to be removed. Heating of the solution can be combined withaerosol generation and/or with vacuum.

In a biodiesel production process, such evaporative methods can be usedto remove alcohol and/or water from biodiesel or from glycerol. Suchremoval is advantageous, for example, to clean the respective solution.

In many cases, following vaporization, it is desirable to recondense thevaporized components, e.g., for alcohol recovery. This can be done instep fashion to provide one-step purification. Indeed, while the energyinput is large, full distillation can be used, thereby providingsimultaneous purification of all components in the solution.

E. Alcohol Extraction and Recovery

In certain systems, it is advantageous to remove and/or recoverunreacted alcohol from the crude biodiesel solution and/or the glycerolproduct. Such alcohol can be obtained essentially purified, or can beco-recovered with catalyst. In the separation of biodiesel fromglycerol, generally a large amount of the alcohol and most of thecharged components will be carried in the glycerol phase. These speciescan be substantially removed from the glycerol, for example, using heatand/or vacuum evaporation followed by condensation or usingnanofiltration or a combination of those methods.

Evaporative methods using heat for vaporization can be full distillationmethods in which all components of the solution are vaporized, and theliquid components re-condensed, or only the more volatile components(e.g., water and alcohol) can be vaporized and re-condensed.

Beneficially, when using heat vaporization, a substantial amount of theheat can be recaptured using heat exchangers. Such heat exchangers can,for example, recover some of the initially generated heat that was notcaptured in heating the solution and/or to capture heat in conjunctionwith re-condensation of vaporized liquids. The recaptured heat can beused in heating steps earlier in the biodiesel production process, e.g.,to heat the incoming glyceride solution feedstock.

In most cases, when using vacuum evaporation, only the volatilecomponents are evaporated, leaving the glycerol.

In either heat or vacuum evaporative methods, the process can beaccelerated by increasing the surface area, e.g., by spraying through anorifice (e.g., a nozzle) to create small droplets (e.g., an aerosol) sothat the surface area for evaporation is greatly increased.

As an alternative or as a method used in conjunction with vaporizationmethods, nanofiltration (NF) can be used to separate solution componentsbased on molecular size (although charge can also participate). In suchfiltration a final membrane is selected that has a molecular weightcut-off (MWCO) such that a significant percentage of the glycerol isretained and smaller species such as methanol (and preferably smallions) will pass through. (MWCO is commonly defined as the MW at which90% of a reference species is rejected, i.e., retained.) For example, amembrane with an MWCO of about 50 will retain a large fraction of theglycerol and pass a large fraction of the methanol. Depending on thecharacteristics of the membrane, the Na, K, and/or OH ions may eitherpass or be retained. Membranes with slightly larger MWCOs can also beused. For example, a membrane with a MWCO of about 100 will retain asignificant fraction of the glycerol; the percentage retained can beincreased by multiple passes through such membranes, with each passresulting in a partial retention (e.g., retention of at least 30, 40,50, 60, or 70%) and the number of membrane passes selected to result inthe desired total separation level. The retentates from the multiplemembrane passages can, if desired, be pooled. The methanol, or methanoland catalyst ion solution, can then be reused in the biodiesel process.

In certain system variants, the catalyst is re-used without fullpurification by evaporating a portion of the glycerol followingseparation from biodiesel. The glycerol fraction contains catalyst thatpartitioned into the glycerol phase. Evaporation of the glycerol willalso evaporate the alcohol (if not previously evaporated) leaving asolution that is concentrated in catalyst. That concentrate can bediluted with suitable alcohol and re-used in the reaction, where therelatively small amount of glycerol does not prevent reaction ofglyceride solution to biodiesel.

F. Exemplary System and Operation

The present systems can be configured in various ways depending on theparticular application and the selection of components. Exemplaryconfigurations are described below.

1. Exemplary Systems Having a Processor Mixer and Flow-ThroughSeparation Tank

Certain examples of the present systems include a single processormixer, a flow-through separation tank, and other accessory componentsfor completing the system. In general, such systems include a highturbulence processor mixer and/or zonal flow-through separation tank asdescribed herein.

A simple but effective exemplary system can include basic components asillustrated in FIG. 1. In operation, alcohol (e.g., methanol) and a 30%sodium methyoxide solution are metered together in the proper proportionfrom respective sources 20 and 10, then this solution is metered intothe flow of raw vegetable oil (e.g., canola oil) from oil source 30.These are mixed using an in-line mixer (not shown in FIG. 1) and passedthrough a heater 40 to bring the mixture temperature to at least 48.9degrees C. (120 degrees F.).

This heated mixture then passes through a specially designed processormixer 50 that emulsifies the alcohol/oil mixture to maximizephase-to-phase contact and thus increase the reaction rate. (Additionalprocessors 70 and 72 are optional. When present they are configured as ascalable system.)

The resulting emulsion then passes through a high-volume recirculationpump 80, through the injection inlet 160 and into the zonal flow-throughseparator tank 100, which has top 102, cylindrical sides 104, andinverted cone bottom 106. Instead of a single pass, fluid can berecycled for more complete reaction. Such recycling fluid can be drawnfrom the recirculation intake port 170 near the bottom of therecirculation zone (area 110 on the flow chart), or from the top of theseparation zone (area 120 on the flow chart) through the biodiesel port180. Throttling valves control the source and flow rate of liquid drawnthrough the recirculation pump.

The emulsified mixture, together with any recirculated liquid isforcefully injected into the center of the top of the tank to effect amixing and circulating action, thus maintaining a relatively homogenousmixture in zone 110 by preventing alcohol from separating out of theemulsion and floating to the top where it can no longer react with theoil.

Separation zone 120 is a relatively still area created by the baffleplate 130 and attached skirt 140 that allows time for the glycerol thathas been released from the oil during the trans-esterification reactionto settle to the glycerol accumulation zone 150 in the bottom of thecone 160 and leave the circulation loop. This is beneficial because theglycerol can back-react with the fatty acid methyl esters (biodiesel,the desired end product) and revert back to glycerides (e.g., vegetableoil), the starting material. Continuously removing the glycerol from therecirculation loop where the reaction is taking place thereforeincreases the effective reaction rate and extent of reaction by reducingthe rate of the reverse reaction. Furthermore, separation of theglycerol allows recovery of alcohol and/or catalyst from the glycerol,such that those components can be re-introduced into the processor at anearlier stage.

The alcohol can be removed following separation of the glycerol, or canbe removed (at least partially) prior to the glycerol/biodieselseparation. Removing at least part of the alcohol before such separationincreased the density difference between the glycerol phase and thebiodiesel phase, which results in a cleaner separation.

Glycerol accumulation zone 150 is a cone shaped area where the glycerolsettles while awaiting draining. Glycerol removal is controlled by afloat switch activating a solenoid valve (not shown) on the bottom drain190. The glycerol drained from the bottom of zone 150 flows into thepipe 192 connecting with the vacuum tank 200 for removing methanol fromglycerol. The vacuum tank is located such that the head pressuregenerated by the tall reaction tank is sufficient to push the glycerolthrough the pipe.

The centrifuge 210 is used to separate any remaining glycerol from theester solution, i.e., the biodiesel. It separates the biodiesel andresidual glycerol into two streams that go to their respective vacuumtanks (200 and 202 respectively) to boil out any residual methanol. Thebiodiesel and glycerol can be separated from each other before removingthe excess methanol in order to prevent the reaction equilibrium fromshifting back to the left, or can be removed before such separation(e.g., to assist in creating a good separation of glycerol from thebiodiesel).

The methanol (or other alcohol) vapor that is vacuum boiled from boththe biodiesel and the glycerol passes through the pump 250 that assistedin it recovery from the vacuum tanks and further passed through a heatexchanger 240 to lower it's temperature to prevent excess evaporationfrom the storage tank 224.

The biodiesel is pumped by a gear pump (not shown) out of the vacuumtank 200 to the water wash system 230. This system adds water to thebiodiesel, agitates them together, and then passes the liquid through acentrifuge to remove the water and water-soluble contaminants. Forsimplicity the centrifuge following the water wash system is not shownin FIG. 1. After washing, the biodiesel is pumped into a storage tank220.

The glycerol is pumped directly to storage tank 222 to await furtherpurification, processing, or transport, while the methanol is stored intank 224 or returned to source tank 20 for reuse.

Two exemplary processor mixer designs that can be utilized in biodieselprocesses as illustrated in FIG. 1 (and FIG. 5) are shown in FIGS. 2-4.

FIG. 2 shows a longitudinal cross-section of an exemplary cylindricaldesign high turbulence processor mixer. Process mixer 500 includes afixed outer housing 510 with a generally cylindrical cavity and arotating cylindrical inner body 530. The housing has projections 520extending toward the inner body, and the inner body has projections 540extending toward the outer housing. Rotation of the inner body is drivenby an external power source via shaft 550, while the opposite end of theinner body is supported by stub shaft 580. During use, fluid is pumpedinto the processor mixer via inlet tube 560, progresses through the gapbetween the outer housing and the inner body while being mixed underhigh turbulence conditions by the action of the sets of projectionsunder rotation of the inner body, and exits through outlet tube 570.

FIG. 3 shows a cross-section of an exemplary radial design highturbulence processor mixer 400 useful in the present systems, where thecross-section is taken along a plane that includes the axis of rotationof the rotor as well as the axial fluid inlet pipe. The processor mixerincludes outer housing 410 and inner rotor 420. The rotor is driven froman external power unit via rotor shaft 440. The rotor includes disk 424and vane projections 422, and the housing includes projections 412. Thehousing projections and rotor projections are arranged in concentricrings that alternate radially. On the opposite side of the housing fromthe rotor shaft is fluid inlet pipe 430, with interior channel 432.

FIG. 4 shows a cross-section of the processor mixer shown in FIG. 3,where the cross-section is taken perpendicular to the axis of rotationof the rotor and just above the surface of the rotor, thereby creating aplan view of the rotor surface. In this figure, the dashed circularlines illustrate the paths the housing projections 412 shown in FIG. 3would describe as the rotor rotates. The rotor projections 422 projectfrom the rotor disk and bypass the housing projections. At the housingperiphery is the outlet pipe 450 with interior channel 452 through whichthe fluid will pass as it exits the processor mixer.

2. Exemplary Scalable Systems Having Parallel Linked Processor Mixerswith a Flow-Through Separation Tank

In other exemplary systems, advantageous scalable systems can beconstructed in which a plurality of processor mixers are configured suchthat individual processor mixers can be brought into operation toincrease output, or conversely removed from operation to reduce outputor to allow for servicing without shutting down the entire system.

Systems of this general type can use a single separator (e.g.,flow-through separation tank and/or centrifuge) in common, or may use aplurality of separators, each functionally linked with one or more ofthe processor mixers.

A schematic example of such a system is shown in FIG. 1 as describedabove, except that optional processor mixers 70 and 72 are present. Thesystem includes three processor mixers 50, 70, and 72 connected to zonalflow-through separator tank 100. In this system, any of the processormixers can be shut down while continuing operation of the remainder ofthe system. If the processor mixers are of equal capacity, this can alsobe used to cut the production to ⅔ or ⅓ of full capacity (or converselyto double or triple the production rate of a single processor). Ofcourse, using processor mixers of unequal capacities or using largernumber of paralleled processor mixers allows other fractional productionrates.

3. Exemplary System with Sequential Processor Mixers

Additional exemplary systems incorporate a plurality of sequentiallylinked processor mixers with a residence chamber following eachprocessor mixer. Each set of processor mixer and residence chamber istermed a processor unit. The system will include at least one separator,such as a separation tank (e.g., a present zonal flow-through separationtank and/or a centrifuge). In operation, each processor mixer impartshigh energy turbulent mixing, while the associated residence chamberprovides an interval during which reagents in the well-mixed glyceridesolution react to form lower alkyl fatty acid esters and glycerol. Asregents at the interfaces are depleted and/or products accumulate and/orphases begin to separate, the solution is extensively mixed again in thenext processor mixer thereby providing fresh reagent for reaction. Byprocessing in this manner, the total mixing energy can be reduced whileretaining a desired rate and extent of reaction without recycling ofpartially reacted glyceride solution. In such a processor, the alcoholand catalyst reagents can be mixed using a single addition before thefirst processor mixer, or can be added in increments to maintain anevener concentration of those reagents. That is, alcohol will beconsumed in passage through each processor unit, reaction depleting itsconcentration. The depleted alcohol can be replaced in additionsincrements bringing the alcohol concentration back to the original orother desired concentration.

Such systems can also include a glycerol/biodiesel separator followingeach processor mixer (or following a series of processor units), eitherintegrated with or separate from the residence unit. The inclusion of aseparator assists in driving the reaction toward biodiesel and glycerolproducts by inhibiting the reverse reaction. However, such removal alsoremoves alcohol and catalyst that are in solution in the glycerol. Suchloss can be compensated by adding excess reagents at the beginning, orpreferably by injecting additional reagent during the sequentialprocess, e.g., before the solution enters each processor mixer ordirectly into the processor mixers.

A residence chamber is sized such that the design flow rate will resultin a desired residence time for the glyceride solution in the residencechamber. Such residence time allows the reaction to proceed to aselected extent. After passage through a residence chamber (orsimultaneous with such passage) glycerol can be separated from thereacted glyceride solution (or biodiesel), or the mixture can be passedwithout separation to the next processor unit. Advantageously, removingglycerol assists in driving the reaction to completion.

Addition of alcohol and catalyst can be performed in a single step orincrementally. For example, sufficient alcohol and catalyst can be addedto allow effective reaction during passage through the first processorunit. If glycerol is not removed, the catalyst will remain, but anincremental addition of alcohol can be performed to restore the alcoholconcentration to a desired level. This process can be repeated until thefinal processor unit, at which time the glycerol phase is removed, andthe biodiesel is passed on for cleaning. Alternatively, if glycerol isremoved following passage through the first and/or an intermediateprocessor unit, that glycerol removal also removes unreacted alcohol andcatalyst. Those reactants can be replaced along with replacement ofreacted alcohol allowing effective reaction in the subsequent processorunit.

Advantageously, a residence chamber in such configurations isessentially a pipe. Use of pipes allows for compact construction and arealso amenable to relatively high pressure operation. For example, whileother configurations can be made transportable, high throughput systemsin which pipes are used as residence chambers are particularly adaptableto transportable designs (e.g., constructed such that the maximumdimensions and total space occupied by the system are consistent withtransport, such as transport by truck or train. For example, systems canbe fitted within standard 20 (approximately 34 m³) or 40 foot shippingcontainers approximately 68 m³), e.g., with all processor units locatedwithin one such shipping container. Additional system components, e.g.,biodiesel cleaner and/or methanol extractor(s) can be placed in the sameor additional shipping container or other space. Typically intransportable processors, the reagent supply, and/or biodiesel and/orglycerol storage are external to the transportable containers, or othertransportable structures that hold the active processing components.Transportable processors can even be constructed in more compactconfigurations, e.g., occupying no more than 5, 10, 15, 20, 25, or 30m³.

In addition, another major benefit of having the processing units andresidence chambers in a container(s) is that the system can be wellinsulated to conserve energy. Such insulation can be used to conserveenergy, even if individual components are left uninsulated, e.g., toincrease ease of inspection, maintenance, or repair. Thus, certain ofthe present processors have uninsulated processor mixers and residencechambers installed within an insulated container(s).

A further advantageous selection is to utilize combinationpump/processor mixers (e.g., as described herein). Such selectionsimplifies the system by reducing the number of different dynamiccomponents.

A schematic example showing a series of processor units in such asequential arrangement is shown in FIG. 5, illustrating sequentialprocessor 300. In this example, there is a series of three processorunits 310, 312, and 314. Each processor mixer is followed by a residencechamber in the form of pipe sections 330, 332, and 334, which haveinternal baffling to maintain mixing. Following each residence unit is acentrifuge (items 320, 322, and 324) to separate glycerol frombiodiesel. Replacement alcohol and catalyst is injected via injectionlines 360 and 362 just before the second and third processor mixers. Theglycerol separated in each centrifuge is combined in pipe 340 anddirected to an evaporative separator 352 in which alcohol is removedfrom the glycerol and combined with residual alcohol removed from thebiodiesel stream in evaporative separator 350 and is re-condensed,passed through pump 372, and passed through heat exchanger 374. Theglycerol can be stored in tank 382 or can be cleaned, e.g., bydistillation.

Following the final processor unit 314 and residence chamber 334, thebiodiesel fraction from the final centrifuge 324 is processed usingevaporative separator 350 to remove residual alcohol, passed throughcentrifuge 326 to separate residual glycerol and associated components,then washed using washer 370. (The glycerol phase removed in centrifuge326 can alternatively be directed to pipe 340 where it is combined withearlier separated glycerol and passed through evaporative separator 352to remove any residual alcohol.) The bulk of the wash water is removedusing a centrifuge 328. Residual water can be removed using anadditional evaporative separator (not shown). The cleaned biodiesel isthen directed to storage tank 380.

4. Phase Inversion Separation System

In general, biodiesel systems include separation steps in which phaseseparation between biodiesel and glycerol is performed. In describedsystems using basic catalysis, the process typically involves adding10-30% v/v of methanol or other lower alcohol. The glycerol produced,together with the majority of the excess methanol forms a denser, lowerphase, with an upper biodiesel phase.

Alternatively, it is possible to cause a phase inversion in which theglycerol-containing phase is less dense than the oil phase and thereforerises to the top. This can be accomplished by adding a larger excess ofthe alcohol (at least for methanol and ethanol). Methanol and ethanolare somewhat less dense than most biodiesel (and glyceride solutions).In these cases, a large excess of the alcohol will cause the combinedalcohol/glycerol phase to be less dense than the biodiesel so that itforms an upper layer. This procedure can be advantageous because theexcess of alcohol reactant helps drive the transesterification to theright (to biodiesel and glycerol products).

However, in order to be economic, recovery of the alcohol is desirable(e.g., for re-use in the biodiesel process). Advantageously, the largeamount of un-reacted alcohol is separated from the glycerol and returnedfor reuse in the process. Such recovery can be accomplished such thatthe alcohol is substantially purified, e.g., by evaporation andcondensation. In this case, the alcohol along with fresh catalyst isadded at the beginning or earlier stage of the process. Alternatively,the alcohol can be co-recovered with catalyst, e.g., by use ofnanofiltration. In this case, the recovered alcohol/catalyst solutioncan be used directly, or additional alcohol can be mixed into thesolution to create a desired alcohol ratio.

All patents and other references cited in the specification areindicative of the level of skill of those skilled in the art to whichthe invention pertains, and are incorporated by reference in theirentireties, including any tables and figures, to the same extent as ifeach reference had been incorporated by reference in its entiretyindividually.

One skilled in the art would readily appreciate that the presentinvention is well adapted to obtain the ends and advantages mentioned,as well as those inherent therein. The methods, variances, andcompositions described herein as presently representative of preferredembodiments are exemplary and are not intended as limitations on thescope of the invention. Changes therein and other uses will occur tothose skilled in the art, which are encompassed within the spirit of theinvention, are defined by the scope of the claims.

It will be readily apparent to one skilled in the art that varyingsubstitutions and modifications may be made to the invention disclosedherein without departing from the scope and spirit of the invention. Forexample, variations can be made to the design of a processor mixerand/or the method of separating glycerol from biodiesel. Thus, suchadditional embodiments are within the scope of the present invention andthe following claims.

The invention illustratively described herein suitably may be practicedin the absence of any element or elements, limitation or limitationswhich is not specifically disclosed herein. Thus, for example, in eachinstance herein any of the terms “comprising”, “consisting essentiallyof” and “consisting of” may be replaced with either of the other twoterms. The terms and expressions which have been employed are used asterms of description and not of limitation, and there is no intentionthat in the use of such terms and expressions of excluding anyequivalents of the features shown and described or portions thereof, butit is recognized that various modifications are possible within thescope of the invention claimed. Thus, it should be understood thatalthough the present invention has been specifically disclosed bypreferred embodiments and optional features, modification and variationof the concepts herein disclosed may be resorted to by those skilled inthe art, and that such modifications and variations are considered to bewithin the scope of this invention as defined by the appended claims.

In addition, where features or aspects of the invention are described interms of Markush groups or other grouping of alternatives, those skilledin the art will recognize that the invention is also thereby describedin terms of any individual member or subgroup of members of the Markushgroup or other group.

Also, unless indicated to the contrary, where various numerical valuesare provided for embodiments, additional embodiments are described bytaking any 2 different values as the endpoints of a range. Such rangesare also within the scope of the described invention.

Thus, additional embodiments are within the scope of the invention andwithin the following claims.

1. A continuous flow biodiesel processor for producing a lower alkylfatty acid ester biodiesel from a glyceride solution, comprising a highturbulence flow-through processor mixer, a flow-throughglycerol/biodiesel separator, wherein said glycerol/biodiesel separatorreceives output from said processor mixer, wherein glycerol is removed;and a biodiesel cleaner receiving biodiesel separated in said separatortank and removing polar components from said biodiesel.
 2. The processorof claim 1, wherein said high turbulence flow-through processor mixercomprises a fluid cavity with proximate opposing surfaces, wherein saidopposing surfaces comprise projections, and wherein at least one of saidopposing surfaces rotates during use such that there is a relativevelocity between said surfaces.
 3. The processor of claim 2, whereinsaid first projections and said second projections bypass duringrotation. 4-9. (canceled)
 10. The processor of claim 2, wherein saidprocessor mixer comprises a housing and a generally circular rotortherein having a first face and a second face, wherein said rotorcomprises a first set of projections on at least one of said first andsecond faces and said housing comprises a second set of projections onan inner surface proximate to said rotor face comprising said first setof projections.
 11. The processor of claim 10, wherein said first set ofprojections consists essentially of a set of vanes.
 12. The processor ofclaim 11, wherein said vanes include a set of concentric gaps, and saidsecond set of projections include a matching set of concentric rings ofprojections that fit within said gaps. 13-16. (canceled)
 17. Theprocessor of claim 1, wherein said glycerol/biodiesel separatorcomprises a zonal flow-through separation tank, wherein said tankreceives output from said processor mixer; and wherein flow of partiallyreacted glyceride solution through said tank establishes a mixing zone,a separation zone, and a glycerol accumulation zone and accumulation ofglycerol creates a glycerol/biodiesel interface within said tank, andglycerol below said interface is removed; 18-20. (canceled)
 21. Theprocessor of claim 17, wherein said zonal flow-through separator tankcomprises a tank of sufficient height and proportions that followinginjection of partially reacted glyceride solution in the top of saidtank there is created a substantially stable upper mixed zone, a centralstagnant zone, and a lower separated glycerol zone. 22-30. (canceled)31. The processor of claim 1, wherein said biodiesel cleaner comprisesan ionically charged solid phase medium.
 32. (canceled)
 33. Theprocessor of claim 1, further comprising at least one alcohol separator,wherein said separator removes alcohol from said biodiesel or from saidglycerol or both. 34-47. (canceled)
 48. A scalable processor forproduction of biodiesel, comprising a plurality of parallel-linked highturbulence flow-through processor mixers which can be operated or idledindependently to produce a biodiesel solution from a glyceride solution;at least one flow-through glycerol/biodiesel separator functionallylinked with said mixers to accept a glycerol/biodiesel mixture processedthrough at least one of said processor mixers; at least one biodieselcleaner functionally linked with said glycerol/biodiesel separator toseparate polar components from said biodiesel solution.
 49. (canceled)50. The processor of claim 48, wherein said high turbulence flow-throughprocessor mixer comprises a fluid cavity with proximate opposingsurfaces, wherein said opposing surfaces comprise projections, andwherein at least one of said opposing surfaces rotates during use suchthat there is a relative velocity between said surfaces.
 51. (canceled)52. The processor of claim 50, wherein said processor mixer comprises ahollow outer housing comprising an inner surface having a plurality offirst projections, and a proximate spaced apart inner body having anouter surface comprising a plurality of second projections, wherein saidouter housing and said inner body rotate relative to each other. 53-95.(canceled)
 96. A processor for production of biodiesel from a glyceridesolution comprising a sequentially linked plurality of processor units,wherein each said processor unit comprises a high turbulenceflow-through processor mixer; and a residence chamber following saidprocessor mixer; a linked glycerol/biodiesel separator receiving reactedglyceride solution from said processor unit; and a biodiesel cleanerreceiving biodiesel from said separator. 97-105. (canceled)
 106. Theprocessor of claim 96, wherein said processing system is transportable.107. The processor of claim 106, wherein said processor units areinstalled in a volume not exceeding 70 m³. 108-109. (canceled)
 110. Theprocessor of claim 96, wherein said high turbulence flow-throughprocessor mixer comprises a fluid cavity with proximate opposingsurfaces, wherein said opposing surfaces comprise projections, andwherein at least one of said opposing surfaces rotates during use suchthat there is a relative velocity between said surfaces.
 111. Theprocessor of claim 110, wherein said first projections and said secondprojections bypass during rotation. 112-124. (canceled)
 125. Theprocessor of claim 96, wherein said glycerol/biodiesel separatorcomprises a zonal flow-through separation tank, wherein said tankreceives output from said processor mixer; and wherein flow of partiallyreacted glyceride solution through said tank establishes a mixing zone,a separation zone, and a glycerol accumulation zone and accumulation ofglycerol creates a glycerol/biodiesel interface within said tank, andglycerol below said interface is removed;
 126. The processor of claim125, wherein said zonal flow-through separator tank comprises an uppermixing zone, a middle separation zone separated from said upper mixingzone by a baffle plate, and a lower glycerol accumulation zone. 127-201.(canceled)